Four Milwaukee police officers were charged Tuesday with felonies related to illegal rectal searches of suspects on the street and in police district stations over the past two years.

In one case, an officer held a gun to a man's head as two others held his arms and a third put him in a choke hold while jamming a hand into his anus, purportedly searching for evidence, according to the criminal complaint. Another man bled from his rectum for several days after his encounter with police, the complaint says.

The complaint lays out in graphic detail how the primary suspect, Officer Michael Vagnini, conducted searches of men's anal and scrotal areas, often inserting his fingers into their rectums. Vagnini acknowledged performing one of the searches. At least one suspect said Vagnini planted drugs on him.

State law and police procedures prohibit officers from conducting cavity searches. Only medical personnel are allowed to perform them, and police must first obtain a search warrant.

At a news conference Tuesday, Flynn differentiated among the allegations, calling the earlier incidents "error" and the illegal searches "willful misconduct."

"Crime cannot be fought with criminality," he said. "A hard-earned reputation has been tarnished."

Vagnini faces 25 counts and was the only officer charged with sexual assault. The most serious charge against Vagnini - second-degree sexual assault - carries a maximum penaltyof 25 years in prison and 15 years on supervision. He faces four counts.

Officer Jeffrey Dollhopf faces two counts of misconduct in public office and one count each of conducting an illegal cavity search and an illegal strip search, both as party to a crime. Officers Jacob Knight and Brian Kozelek each face one count of misconduct in public office. Knight faces one count of being a party to the crime of an illegal cavity search. Kozelek is charged with one count of being a party to the crime of an illegal strip-search.

The misconduct charges are felonies with a maximum possible penalty of 3 1/2 years in prison. The cavity search and strip-search charges are misdemeanors that carry up to 90 days in jail.

Biggest case since '06The case is the biggest criminal prosecution against Milwaukee police officers since 2006, when eight officers were charged in federal court in connection with the beating of Frank Jude Jr. outside a Bay View party in 2004. Seven were convicted.

The charges in the strip-search case were the result of complaints from "dozens and dozens" of citizens, according to Milwaukee County District Attorney John Chisholm. The investigation was based in District 5 on the north side, he said. All the officers charged are white. All the men subjected to the illegal searches are black.

In recent weeks, many in Milwaukee's African-American community, as well the Chicago-based Rainbow-Push coalition, have called for Flynn to resign or be fired.

The chief deflected questions about those demands Tuesday, saying misconduct occurs in every big-city police department.

Mayor Tom Barrett said he backs Flynn.

"I do not support removing the chief at this time," Barrett said. "I think these investigations need to move forward."

Four plead not guiltyThe four officers all pleaded not guilty Tuesday afternoon before Milwaukee County Circuit Judge Jeffrey Wagner, who presided over the secret John Doe investigation into the searches. The officers, who are scheduled for preliminary hearings Nov. 2, and their attorneys declined to comment.

Several other officers who were taken off the streets during the strip-search investigation were not charged. They include Jeffrey Cline and Gregory Kuspa, who also were on the scene of the arrest of Williams, seen on a squad car video gasping for air and begging for help as officers largely ignore him.

Also not charged were Jason Mucha, a sergeant who supervised some of the officers involved in the searches, and Michael Gasser, who said on Facebook he believed he would be cleared.

More than 50 people testified at the John Doe inquiry, 32 of them from the department, according to a news release. Many officers came forward to testify truthfully about behavior they witnessed, Chisholm said. Prosecutors took that into account when deciding whether to charge them, he said.

Lawyers reactJonathan Safran, a lawyer who represents two of the men who said they were assaulted, called the charges "another sad chapter" for the city and the department.

"This is, I am afraid, the tip of the iceberg," he said. "There is a culture in the Milwaukee Police Department that, unfortunately, has led to a number of civil rights violations."

Robin Shellow, a lawyer who represents one of the men prosecutors say was subjected to an illegal search, thanked Assistant District Attorney Miriam Falk for her thorough review of the case.

Shellow called Falk "a warrior in the fight for the civil rights of persons of color."

Like Safran, Shellow said she has spoken with other victims - including the mothers of underage boys - who were afraid to report the abuse because of their own criminal records.

Investigation endsThe charges issued Tuesday mark the end of an investigation that began in March, when the Police Department notified the district attorney's office of the allegations.

At the time, Flynn said the department had been aware of complaints about potentially illegal searches for "a couple of years," but waited to investigate until authorities recognized a pattern.

Flynn took the unusual step of asking other potential victims to come forward.

The criminal complaint details eight illegal searches conducted over two years, from February 2010 to February 2012. Vagnini is alleged to have performed all of the searches. The three other officers are accused of witnessing Vagnini's actions and not stopping them or reporting them to a supervisor.

In one case, a man had gone to check on his aunt's house in the 3500 block of N. 10th St. When he came outside, his vehicle was surrounded by squad cars. Vagnini put his bare hand down the man's pants, touched his scrotum and inserted fingers into his anus, the complaint says. When the man pulled away, Vagnini put him in a choke hold that caused him to slobber onto Vagnini's arm. Vagnini repeatedly told him to "stop resisting" as he pulled back so hard on his neck his feet almost left the ground, the man said. Two other officers held his arms and one put a gun to his head, the complaint says.

Vagnini claimed he found crack cocaine inside the man's anus, but the man insisted it "was not on him prior to the search," the complaint says.

In another search, Vagnini conducted a traffic stop near N. 12th and W. Locust streets, the complaint says. Vagnini handcuffed the driver and asked him for "the drugs." The defendant denied having drugs but actually had hidden drugs inside his anal cavity, according to the complaint.

Vagnini put the suspect in a chokehold from behind, released him and then stuck his gloved hand inside the defendant's underwear, "shoving his fingers deeply into the defendant's butt crack and possibly into the defendant's anus," the complaint says.

The man was screaming, and as a result of Vagnini's actions the man was bleeding from the anal area for several days, the complaint says.

According to the report Vagnini filed, he found a clear plastic baggie containing corner-cuts of cocaine, the complaint says.

Background checkedVagnini was hired in 2004. His department personnel file contains an official reprimand, handed down in 2009, for failure to be civil and courteous toward the public.

Dollhopf was hired in 1995. His personnel record includes a two-day suspension for unsafe vehicle operation in 1999 and an official reprimand for unsafe vehicle operation related to a pursuit in 2010.

Knight, who was hired in 1999, has one official reprimand on his record, for failing to honor a subpoena in 2009.

Kozelek was hired in 2007. The Journal Sentinel did not have a copy of his personnel record Tuesday.

All of the officers have been on the job long enough to know that the types of searches alleged were illegal and against policy, Flynn said.

Michael Tobin, executive director of the Fire and Police Commission, noted that the Police Department asked not only the district attorney but also the FBI and U.S. attorney's office to assist in the investigation "in order to cast the widest possible net into potential criminal activity."

"Rogue officers that are accused of committing crimes in order to obtain evidence don't represent and don't define the entire MPD," Tobin said. "The charges, if proven, are inexcusable and tarnish the badge of every MPD officer."

The next stepTobin said the next step is to determine through a separate internal investigation whether discipline should result.

That investigation is under way, Flynn said Tuesday.

The four officers charged have been suspended with pay. Barrett said he wants them to be removed from the city payroll as soon as legally possible.

"I am disgusted. I am outraged," Barrett said. "If these allegations are true, they represent an egregious violation of the public trust."

The investigation has broader implications than just criminal charges or discipline. Seven people have filed notices claiming they were illegally searched, which is the first step toward filing a civil suit against the city. An eighth plans to file similar notice within the week, Safran said. In at least three cases identified by the Journal Sentinel, charges have been reduced or dismissed after defendants alleged that evidence was obtained illegally.

Pointed reactionState Sen. Lena Taylor (D-Milwaukee) said progress on this one area of police misconduct is not enough.

"This one step cannot replace the need for greater accountability and reform," she said. "Police officers are meant to serve and protect members of our community. Unfortunately, police misconduct continues to put the MPD's honoring of that responsibility in question."

The American Civil Liberties Union of Wisconsin echoed Taylor's calls for outside scrutiny of the department and changes in supervision, training and personnel. The ACLU said it will continue to push for reforms.

"No Milwaukee resident, regardless of the crime rate in their neighborhood, should be subject to sexual assault on our city's streets by police officers," Christopher Ahmuty, executive director, said in a statement. "These charges are an important step in identifying obstacles to professional police service for all Milwaukee neighborhoods and residents."

***Key SuspectOfficer Michael VagniniHired: 2004

Personnel file : An official reprimand, handed down in 2009, for failure to be civil and courteous toward the public.